Lewy body dementia (LBD)

Lewy body dementia (LBD) is one of the most common types of progressive dementia. LBD usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have occasionally been reported.

In LBD, cells die in the brain's cortex, or outer layer, and in a part of the mid-brain called the substantia nigra. Many of the remaining nerve cells in the substantia nigra contain abnormal structures called Lewy bodies that are the hallmark of the disease. Lewy bodies may also appear in the brain's cortex, or outer layer. Lewy bodies contain a protein called alpha-synuclein that has been linked to Parkinson's disease and several other disorders. Researchers, who sometimes refer to these disorders collectively as "synucleinopathies," do not yet know why this protein accumulates inside nerve cells in LBD.

The symptoms of LBD overlap with AD in many ways, and may include memory impairment, poor judgment, and confusion. However, LBD typically also includes visual hallucinations, parkinsonian symptoms such as a shuffling gait and flexed posture, and day-to-day fluctuations in the severity of symptoms. Patients with LBD live an average of 7 years after symptoms begin.

There is no cure for LBD, and treatments are aimed at controlling the parkinsonian and psychiatric symptoms of the disorder. Patients sometimes respond dramatically to treatment with antiparkinsonian drugs and/or cholinesterase inhibitors, such as those used for AD. Some studies indicate that neuroleptic drugs, such as clozapine and olanzapine, also can reduce the psychiatric symptoms of this disease. But neuroleptic drugs may cause severe adverse reactions, so other therapies should be tried first and patients using these drugs should be closely monitored.

Lewy bodies are often found in the brains of people with Parkinson's and AD. These findings suggest that either LBD is related to these other causes of dementia or that the diseases sometimes coexist in the same person.